Some scientists look into outer space while others look elsewhere. Georg Steinhauser looked into his bellybutton and discovered what the lint found there contains and its possible purpose. Mostly made of fabric bits and dead skin, it is most likely used to keep germs and other things out.
It is simply a rhyme scheme. Every alternating line of the poem, the last words rhyme. That is the use of a rhyme scheme. I wouldn't say there is a 'which' to a rhyme scheme.
